1. Field of the Invention
The present invention relates to a top-feed sewing machine with an improved presser device.
2. Background Art
A presser device of interest is disclosed in German Utility Model No. 84 33 111. The disclosures of all prior art materials mentioned herein are expressly incorporated by reference. The known presser device has, inter alia, a feeder foot which has a spur behind its two soles, as seen in the direction of feed of the material being sewn. The bottom of the spur which extends flush with the bottom of the sole rests temporarily on a web portion of the feed dog and thus makes tensionless sewing possible, particularly of thin material.
On the other hand, an intermediate plate can be placed between two layers of material to be sewn together, and between the feeder foot soles and the throat plate in the vicinity of the place of sewing, which prevents the spur from temporarily resting on the mating surface of the feed dog and on the cloth being fed. In this way, the working-in of additional width, for instance for ruffling one of the two layers of sewing material, is made possible.
The disadvantage of this known presser device is that in order to ruffle the upper layer of sewing material, the intermediate plate must be pushed between it and the lower layer of sewing material, and then, to continue the subsequent smooth sewing, if both ruffled and smooth regions are present within the path of a seem, this intermediate plate must be removed. These steps require difficult handling, which results in unproductive downtime.
If, on the other hand, in order to avoid unproductive downtime, the aforementioned intermediate plate is not inserted between the two layers of material before the ruffling is performed, then the following further disadvantage results: When ruffling the upper layer of material, only about half of the intended amount of the additional width can be worked-in, the intended amount of additional width being identical to the feed stroke of the feeder foot. The aforementioned reduced amount of additional width comes about due to the fact that, at the start of the phase of advance, the single-part feeder foot, which is fastened to a swingably suspended foot bar, engages the material being sewn, starting from the vertical and inclined obliquely forward, in the direction toward the operator. In this way, the bottom of the spur of the feeder foot, which spur is arranged behind the sewing needle, contacts the top of the upper layer of the material being sewn while the anti-skid grip side of the sole of the feeder foot has still not come into contact with the upper layer of material. Only when the foot bar, and thus the feeder foot, assumes approximately the vertical position is it possible for the gripping sole to grip the upper layer of material. Since at this time, however, the first half of the feed path has already been consumed, only the second half of the adjusted feed path can thus be suitably used for the intended ruffle formation.